Rechargeable batteries have been in existence for over 100 years and are currently widely used as energy-storage units, especially in portable electrical devices, such as cell phones and laptop computers. In recent years, rechargeable batteries have also received interest as a power source for electric and hybrid electric vehicles.
However, the cycle life of certain batteries remains relatively low based on known problems with these batteries. Problems that reduce the life of a battery can include dendrite growth during cycling between a charging state and a discharging state leading to a short-circuit event by creating a path between negative and positive electrodes, active materials migrating from electrodes leading to a shape change of the electrodes, and active materials of the electrodes dissolving into an electrolyte solution and passing through the electrolyte separator resulting in electrode contamination.
Previous efforts to prevent or minimize these problems have led to the development of relatively thick electrolyte separators. However, increasing the thickness of a separator results in a reduced energy density of the battery. Reducing this thickness leads to relatively weaker mechanical strength of the membrane materials when in a swollen state. For alkaline batteries that are swollen with potassium hydroxide (KOH) solution, the gel tends to become mechanically weak when one tries to reduce its thickness to increase the efficiency of the battery. Also, a sufficient solution for reducing or blocking the dendrite growth has not yet been developed.
Thus, it is desired to provide improved electrolyte membranes. It is further desired to provide electrolyte membranes that improve the properties of rechargeable batteries.